In a conventional motor, a permanent magnet of a rotor is divided in an axial direction to constitute blocks, and the blocks are arranged while being displaced in a circumferential direction so that a skew effect is imparted to the motor. Since the blocks are arranged so as to have axial spaces therebetween, no leakage of magnetic flux is generated in an axial component, and hence, a magnetic flux distribution in a circumferential direction becomes a sine wave, whereby a cogging torque in each block is reduced (for example, Patent Document No. 1).
In addition, skew slots for displacing a stator continuously in a circumferential direction are widely known, and since the phase of cogging torque changes continuously, a summed total cogging torque is reduced.
FIG. 20 is a front view of a rotor of a conventional motor, and FIG. 21 is a side view of the same motor. In FIG. 20, a plurality of permanent magnets 2A are arranged in a circumferential direction on an outer circumference of a rotor 1, and as is shown in FIG. 21, a plurality of permanent magnets 2B are arranged spaced apart from the permanent magnets 2A in an axial direction while being shifted slightly in the circumferential direction as they extend in the axial direction, so as to provide a skew effect. In addition, by providing a gap G2, which is larger than a gap G1 between an S pole and an N pole of the permanent magnets, between the permanent magnets 2A and the permanents magnets 2B, a circumferential magnetic flux distribution of the rotor can be made to be a sine wave.
In this way, in the conventional permanent magnet type synchronous motor, since the permanent magnets of the rotor are displaced in the circumferential direction and the stator core is displaced in the circumferential direction, the cogging torque is reduced.    Patent Document No. 1: Japanese Patent No. 3599066 (page 4, FIGS. 3 and 4).
In addition, FIG. 22 shows a conventional laminated core with no skew provided on a stator core. In the figure, 30 denotes a stator core main body, 33A an initial punched core, 33B a final punched core, 35 a yoke, 35a a yoke fitting portion, 35b a V clamp, 36 a center yoke (a tooth), and 39 a pole piece. Since the shapes of pole pieces 39 of the initial punched core 33A and the final punched core 33B are completely the same, distal ends of the pole pieces 39 of the stator core main body 30 which is made up by laminating a number of stator cores are formed at right angles, and no skew is formed.
In this case, to eliminate cogging, as has been described in FIGS. 20 and 21, the rotor needs to be skewed in place of the stator, and to make this happen, the magnets are laminated together while being shifted from one another.
In this way, in the conventional method, while the following (1) and (2) have been performed, each has its own defect.
(1) In the event that a skew cannot be given to the stator, the magnets need to be shifted in a radial direction on the rotor side so that a skew is given to the rotor, and this work has been complicated.
(2) In addition, in the event that a smooth skew is given to the stator core, a cutting blade has to be prepared for each type of skew given, which has been difficult from the viewpoint of die size and limited production costs.